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Sauron
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Thee and me. However, you also see I'm sure that a lab bench procedure that might work, is not the same as a route to 20-50 Kg/day of product process
(which is still just a prototype or pilot scale) much less an industrial process. I'm not a CE of any sort, just an old wet lab synthesist out to
seed, but even I can see that those anhydrous tansition metal or heavy metal acetates have a rather small percentage of acetate relative to metal and
that therefore even if they are succesfully induced to give off Ac2O there won't be much of it per Kg starting material or Kg of metal oxide fused
crap left in the pot that has to be removed somehow or else the flask needs to be trashed after every run. I used to know a guy who made P2P by dry
distillation of lead acetate and phenylacetic acid, a procedure he found in a 1920s entry in CA from a Japanese forensics journal. Japan had a huge
meth problem 80-90 years ago, and this dry distillation was main process for making phenylacetone. The mix would sit nicely as a melt until the P2P
would flash off and a solid block of lead was left behind in the flask. He tried everything including RFNA to dissolve that but in the end he had to
throw away a lot of 1 iter 3-necked 24/40 flasks.
So let's just say I am skeptical about the practical aspects of making Ac2O from metal acetates the dry way.
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S.C. Wack
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There is nothing wrong with my patent numbers, only the crap sites that you use to look them up.
http://ep.espacenet.com/numberSearch?locale=en_EP
http://patft.uspto.gov/netahtml/PTO/srchnum.htm
Those other things you say K-O says have already come up here also. There is no secret information that only K-O knows. Nor are you the first here to
install Ullmann's or K-O by far. CA (usually), Beilstein, and Gmelin's have everything worth mention. What is missing is the usually foreign-language
journals that they reference that give the essential details that none of the blurbs ever contain.
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Sauron
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I have been using www.freepatentsonline for several years and while I think their search engine sucks, for a situation where I have patent number they
are fast and reliable and easy. And they are free. Recently they did a redesign and perhaps they now have a cutoff date, which would be annoying if
true. Previously older patents were not available except as PDF or TIFF images but they were available. I have many many such patents retrieved from
this site.
I do not share your view that this site is "crap" - a description you also chose to apply previously to my browser for no apparent reason, without
even knowing which browser it was.
So I am obliged to come to the conclusion that you are an ill mannered, ill tempered lout of a curmudgeon and unfit for human society. Rarely have I
encountered as obnoxious a piece of work as you. Kindly stay the hell away from my posts in the future. I am not interested in communicating with you
in any fashion.
By the way and FYI I used to suscribe to Delphion when it was $75 a month. Then Thomson took it over and it quickly climbed to $125 a month and I
cancelled. In my experience www.freepatentsonline is almost as useful as Dephion used to be but without the rapine and avarice that Thomson
introduced.
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S.C. Wack
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| Quote: | Originally posted by Sauron
Kindly stay the hell away from my posts in the future. I am not interested in communicating with you in any fashion. |
This does not match what you said above. You asked and I replied. Tough shit if you don't like what I have to say. You say a perfectly fine image must
be resized in your erased post, so I call bullshit on your browser. So what? You can't find US patents with your crap patent-finding sites, so you
know what? That makes them crap sites. Really. I will not hesitate to say whatever I feel appropriate in response to your posts, so sorry. No trolling
or games, just an honest desire for a better forum combined with straight talk. Read all of my posts, and the many posts that I haven't made, and see
if this can be doubted. Feel free to argue with any and all of my posts as well. Now, don't get the impression that I actually care what you think...
On-topic, to clarify my point about K-O, it is a great compact reference for certain data, but it gives false impressions due to the spare language
that it uses, and its references when looked up are generally impractical on anything but an industrial scale.
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jimmyboy
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ooooo catfight.. you guys are totally ridiculous... can we please focus on the question at hand here -- if you want to flame each other take it to
private messages...
Anyways i was wondering about just drying out glacial acetic acid with sodium...
Acetic anhydride can also be dried by standing with Na wire for up to a week, removing the Na and distilling from it under
vacuum. (Purification of Laboratory Chemicals 4ed. pg 66)
Since all the other routes involve ketene and hydrogen sulfide and all sorts of wonderful nasties.. as far as i know sodium won't kill you - it may
burn or blow up under the right conditions but it wont make you die usually.. and is fairly easy to make as well - slow but makeable -- this won't be
fast (a week) -- but you won't have to worry about fume hoods or the batf knocking down your front door.. the only other drying agent i saw was
P2O5..
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Sauron
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"Drying" Ac2O is a unique concept since Ac2O reacts with water, and is a well known dehydrating agent for many reactions itself.
Likewise any mixture of AcOH and Ac2O that contained moisture, would not contain moisture for long, would it? Save your Na wire for something that
needs it.
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not_important
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| Quote: | Originally posted by jimmyboy...
Anyways i was wondering about just drying out glacial acetic acid with sodium...
Acetic anhydride can also be dried by standing with Na wire for up to a week, removing the Na and distilling from it under
vacuum. (Purification of Laboratory Chemicals 4ed. pg 66)
... |
Acetic anhydride doesn't react with sodium in the cold, it has no free reactive/acidic hydrogen. The sodium reacts with traces of water and/or acetic
acid in the anhydride.
Acetic acid does have an acidic hydrogen, which will react with sodium to give hydrogen and sodium acetate and a fair amount of energy. As
someone who has tossed a 2.5 kg chunk of sodium into water, I can say that such reactions can be quite exciting and best viewed from a distance.
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Per
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| Quote: | | 2 NaOOCCH3 + 2 N2O4 -> (CH3CO)2O + 2 NaNO2 + N2O3 |
Thanks Sauron, that seems to be a great reaktion if it´s working.
NO2 is easy to make but I tried to condense it further and it doesn´t work althougt it´s boiling point is 21°C.
Have the N2O4 and NaOOCCH3 are only mixed in the cold or is there something else to look after?
Don´t know if it´s discussed in this board further so I´m asking for it here, how can NO2 condensed to N2O4?
Is a Liebig-cooler and -10°C enougt?
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jimmyboy
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Well - it doesnt give many details on the how and technique used in the book -- I had my doubts as well - I guess we are kind of stuck with a ketene
lamp and a ton of scrubbers..
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Sauron
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I'd go lower than -10 for the coolant, and use a high surface area condenser rather than a simple Liebig.
I was told that this reaction was mentioned earlier in the thread but I have not been able to locate those posts so far.
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S.C. Wack
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The abstract strongly suggests that the N2O4 was in the gas phase and does not mention temperature, amounts used, time, etc.
edit:
http://www.sciencemadness.org/talk/viewthread.php?tid=1937
http://www.uspto.gov/patft/help/images.htm
The images display fine for me, but I rarely use uspto, and all of my direct patent links that I post are to espacenet pdf. They have available pretty
much every patent ever, however. Pre-1976 patents are as TIFF, that is just how it is, and even alternatiff is better than chem patents in HTML or
whatever that is as on newer patents and other sites IMHO.
[Edited on 25-3-2007 by S.C. Wack]
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Sauron
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I just went to the UG Patent Office web site as recommended by one of our illustrious fellow members located at
http://patft.uspto.gov/netahtml/PTO/srchnum.htm
and I pasted in the US patent number he cited into the box indicated and was informed full test was unavailable and to click on IMAGES. I did so and
sat and waited and waited and waited.
Nothing came up.
What bullshit is this?
US1856251
US1870601
Anyone else have any luck retrieving these rather elderly patents? If so kindly post the pdf's here.
I have retrieved hundreds of patents over the years some of them older than these, without any difficulty.
[Edited on 25-3-2007 by Sauron]
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not_important
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| Quote: | Originally posted by Sauron
I just went to the UG Patent Office web site as recommended by one of our illustrious fellow members located at
http://patft.uspto.gov/netahtml/PTO/srchnum.htm
and I pasted in the US patent number he cited into the box indicated and was informed full test was unavailable and to click on IMAGES. I did so and
sat and waited and waited and waited.
Nothing came up.
What bullshit is this?
... |
Do you have a TIFF viewer plugin?
.
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Sauron
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I have Photoshop and ACDC both recent versions. When www.freepatentsonline.com pulls up an older patent which they do from same USPTO database they give me a choice between TIFF and PDF. I never did
get TIFF to work right, but PDF always works.
Why won't these TIFF images just come up in Photoshop or ACDC?
Anyway I Googled "TIFF viewer plugin. One of the links was to the USPTO site so I went there and they linked to a plugin called InnoVUE 7.0. I
downloaded and installed it. It halfway worked, in that I could now view the patent images but as soon as I tried to save it shut down my browser.
Several times. So I uninstalled it. Went and found another plugin called AlternaTIFF and this one works fine.
I still do not see why this is necessary. But whatever. I now have these two old and admirably brief patents so I can see whether or not they were
worth the bother.
I suppose all this is because TIFF is not a native Internet graphic format like GIF, JPG or PNG? However that then begs the question of why USPTO
used TIFF instead of JPG damn it. I hate having to jump through hoops for bullshit like this.
Fortunately the two patents were indeed interesting and if in fact they work, useful. The second one of more limited utility because it depends on
access to 1,1,1-trichloroethane which is banned in many places.
[Edited on 25-3-2007 by Sauron]
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Eclectic
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Have a look at http://www.espacenet.com/
You can do worldwide patent searches and download the complete patent in one PDF.
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Sauron
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Thanks @Eclectic.
Hmmm. If 1,1,1-trichloroethane can be hydrolyzed by water and catalyst (H2SO4) in an autoclave to acetic acid, acetyl chloride, or acetic anhydride
(depending on ratio of water to tric) then doesn't it seem reasonable that hexachloroethane would hydrolyze to oxalic acid or oxalyl chloride
similarly? There isn't any oxalic anhydride of course.
On the other hand hexachloroethane is a solid so one of the conditions (raising it above bp at normal pressure) might be a trifle hard.
Just thinking out loud.
The reaction described in US 1,856,251 is between vinyl acetate and acetic acid in presence of acid catalyst e.g. H2SO4, ZnCl2, CoCl3, Cl2, FeCl2 etc.
Liquid phase reflux 10 hrs with stripping of acetaldehyde formed through a fractionating column. Claim is made that 77% acetic anhydride present in
reaction mix (after acetaldehyde removed) along with unreacted VA and by product ethylidene diacetate, and that fractionation of this mix allows 95%
recovery of that Ac2O.
Industrially this facile process (even if it works) would be of limited value since after all, how is VA made? From Ac2O and acetaldehyde. However for
the rest of us this process may well be highly useful.
Compare to Gulf Research's reported reaction of vinyl acetate in AcOH soln containing sodium acetate and catalyzed by PdCl2. This requires 24 hrs,
with 55% conversion of VA to approximately equimolar amounts of acetaldehyde and Ac2O. The catalyst cost is high (about one mol (177 g) PdCl2 per Kg
Ac2O produced) and that is expensive even though PdCl2 is not consumed and can be reused. ZnCl2 was inactive with these reactants under these
conditions.
An obvious difference is that the patented reaction employs the carboxylic acid as reactant with VA while the Pd(II) catalyzed reaction employs sodium
acetate. An examination of the mass balance indicates that the sum of the masses of the Ac2O and acetaldehyde produced is greater than the VA
consumed. As the reaction will not proceed in absence of the sodium acetate it appears that sodium acetate is being consumed. Perhaps it is
regenerated from the AcOH solvent in which case the amount of solvent will be down. The authors are silent on these points. In any case ecpnomically
this reaction with this catalyst is as dead as a herring in the moonlight.
The patented reaction produces acetaldehyde which can be oxidized to AcOH and utilized in next batch; and ethylidene diacetate which is added to next
batch and is alco converted to Ac2O and acetaldehyde. All this is attractive and convenient - if it works.
[Edited on 26-3-2007 by Sauron]
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12AX7
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| Quote: | Originally posted by Sauron
There isn't any oxalic anhydride of course. |
Why not? And why not polyanhydride species?
Tim
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not_important
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The anhydride would be a three member ring - an oxirane - with the additional strain caused by the two carbonyl oxygens. A polymeric, even dimeric,
compound would have less such stress, true.
You can get oxalic anhydride as a transition state or under goodly amount of pressure.
Attachment: oxalate_from_CO2&CO.pdf (345kB)
This file has been downloaded 2253 times
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Sauron
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Even oxalyl chloride isn't quite as stable as we would like, which has always limited its utility beyond the bench scale.
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Per
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| Quote: | | I'd go lower than -10 for the coolant, and use a high surface area condenser rather than a simple Liebig. |
Ok, then I´ll try it again with -20°C cool alcohol.
When I find the time for the experiment I´ll try it out and post here my experience, but that can take still much time, because I´ve some other
thing to do.
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Sauron
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Liquification is only necessary (I suspect) if you want to accumulate and store N2O4 in a Dewar or cylinder.
Else just generate and dry it and run it into the reactor as it forms.
Also, did you see the posts on vinyl acetate acetylation?
Vinyl acetate is cheap and readily available. VA + acetic acid catalyzed by mineral acids or Lewis acids -> acetaldehyde and acetic anhydride.
Claimed 77% Ac2O in product mic and 95% recovery of that. H2SO4 suffices. HCl and HBr also work. Lewis acids divalent chlorides of Zn, Cu, Fe. Also
arylsulfonic acids and sufur halides claimed. See US patent referenced above.
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Per
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I think it´s much more convenient to work with solid N2O4 than with NO2 gas, also the yield should be higher if a solid is used, but if I can´t
condense the NO2 I´ll try it with the gas.
Firstly I prefer this method because I claime all necessary chems for it and because NaNO2 is also obtained, but the vinyl acetat method seems also to
be very interested.
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Sauron
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I'm sure many of us look forward to hearing how the N2O4 method works out.
Good luck with it!
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garage chemist
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I would use gaseous NO2, lead through anhydrous powdered NaOAc in a glass tube if I were to try this process.
NO2 is not so easy to dry- H2SO4 reacts with it, forming nitrosylsulfuric acid. CaCl2 would form nitrosyl chloride, at least to some extent. Silica
gel would probably adsorb NO2.
What would be a preferred method of drying NO2? P2O5, yes that would be ideal, but not suitable if the gas is quite wet in the beginning. A drying
agent with higher capacity, and not so high intensity, is needed first.
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Sauron
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Brauer gives drying directions. His prep of N2O4 is from lead nitrate. He freezes out the majority of moisture with first trap at -10--20 C, then
passes through PbO2 and finally P2O5 before liquifying at -78 C (obviously dry ice/acetone trap).
Gives a tantalizying reference to extra pure N2O4/NO2 from N2O5 but I don't think that is necessary for this purpose.
Pages 488-489 from Brauer attached.
[Edited on 30-3-2007 by Sauron]
Attachment: Pages from brauer_ocr.pdf (79kB)
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